Elevator



A. BfsEE ELEVATOR Nov. 13, 1934.

Filed Oct. 19. 19 31 /z y /a INVENTOR A044 5- SEE.

Patented Nov. 13, 1934 UNITED STATES ELEVATOR Alva B. Sec, Greenwich,

Conn., assignor to A. B.

Sec Elevator Company, Inc., a corporation of Delaware Application October 19,

9 Claims.

In elevator systems, motion is transmitted from ra driving motor to the elevator car through a 1traction drum and cable. Commonly, the cable is secured to the elevator car at one end, is wound around the drum which is located in the overhead structure, and is secured at the opposite end to a counterweight. The weight of the car and the counterweight acting on the cable cause the cable to embrace the drum with such force that the friction between the drum and the cable is sufficient to transmit movement of the drum to the cable. In the upper limit of travel of the elevator car, the counterweight rests upon a bumper at the bottom of the shaftway and the cable sags. However, in high buildings the weight of the cable in this position of the car exerts suflicient force upon the cable to cause such frictional contact of -the cable and drum as to maintain the traction of the cable and the car continues to move in response to movements of the drum. Consequently, if through failure of the limit switch at the upper limit of travel of the elevator car, the traction drum continues to rotate, the car will be drawn into the overhead structure, and to provide a means for relieving the force exerted on the drum by the weight of the cable, and thereby preventing the possi-- bility of the car being drawn into the overhead structure by continued movement of the driving motor, after the car has reached the upper limit of its movement, is the object of my invention.

In accordance with my invention, I provide a gripping device which grips the cable, when the elevator car reaches the upper limit of its travel, and relieves the traction drum of the weight of the cable, thereby permitting the traction drum to rotate without movement of the cable and the car. This gripping device consists of a pair of members movable with respect to each other having opposed gripping surfaces between which gripping surfaces the cable of the elevator system is adapted to move. One of the members is adapted to be moved relative to the other into gripping position when the car reaches the upper limit of travel, and securely grip the cable between its gripping surface and the gripping ,surface of the other member.

When the elevator car reaches the upper limit of its movement, the cables by virtue of their great weight have considerable momentum and the kinetic energy of the moving cables is dissipated suddenly upon the operation of the gripping device to stop and hold the cables. In order to absorb this energy without serious shock to the overhead structure, the gripping device of my invention is constructed to absorb the shock or dissipate the energy incident to stopping the moving cables, without transmitting that energy 1931, Serial No. 569,615

as a sudden shock to the overhead structure upon which the gripping device is mounted.

Specifically, one of the gripping members of the gripping device is adapted to move in and relative to the other. This inner member is adapted to be moved relative to the outer mem her into gripping position by'the action of the force of gravity acting thereon, and it moves into and out of gripping position with its gripping surface constantly parallel to the gripping'surface of the outer member throughout the limit of its movement. The inner member is held against movement under the force of gravity acting thereon by a latch. This latch is so constructed that it normally rests in the latched position. It is provided with a cam follower which extends into the elevator shaftway and which is adapted to cooperate with a cam on the elevator car for releasing the latch, thereby permitting the inner member to move into gripping position. v The two members are resiliently mounted on a base which is adapted to be secured to the overhead structure. This resilient mounting, which may include compression springs, is such that the total energy of the moving cables is absorbed by the resiliency of the mounting. Thus, when the inner member moves into gripping position and the moving cables are gripped between the two members, the members move together against the action of the resilient support and the energy of the moving cableis dissipated in the compression of the resilient members of the support.

The invention will be more clearly understood and the advantages thereof more apparent from the following particular description of the embodiments thereof illustrated in the accompanying drawing in which:

Fig. 1 is a diagrammatic representation of an elevator system utilizing the gripping device of my invention;

Fig. 2 is an enlarged side elevation of a gripping device with a guide plate of the support removed; and

Fig. 3 is an enlarged side elevation of a modified form of the gripping device.

The elevator system, in connection with which the device of my invention is shown, comprises an elevator car 1 which is adapted to travel in a vertical plane and adriving motor 2 for operating the elevator car. On the shaft 3 of the driving motor, which is mounted on the overhead structure, there is a traction drum 4. Beneath the beam on which the driving motor is mounted, there is mounted an idle drum 5 which is spaced from the drum on theshaft of the driving motor and which cooperates therewith. A cable 6 is secured at one end to the elevator car and is doubly wrapped around the two drums 4 and 5; the other end of the cable extends over the lower drum into the shaftway and is secured the drums to the cable and through the'cable't'o the elevator car.

At the bottom of the shaft in the plane of travel of the counterweight, there'isprovlded a bumper on which the counterweight rests when the, elevator car is in the upper limit of its move ment. This bumper serves to absorb the force of the counterweightso as to relieve the cable of thatforce and lessen the frictional contact between the cable and. the driving drum. In large buildings, however, the weight of the cable itself exerts a force upon the cable, which force'is adequate to cause the cable to frictionally engage the driving drum with sufficient friction to transmit motion of the driving drum to the elevator car. In such cases when, through failure of the limit "switch or failure of some other part of the control mechanism, the driving drum continues to rotate after the elevator car has reached the upper limit of its movement, the car will be,

drawn up into and crushed against the overhead structure. .To avoid this possibility of over travel of the elevator car, I provide a gripping device designated generally by the numeral 11 which isadapted to grip the cable, when the elevator car reaches the upper limit of its travel, and relieve the driving drum of the weight of the cable.

The'gripping device (shown enlarged in Fig.

'2), comprises an outer member 12 and an inner 'member 13,mov'able relative thereto.

v The outer member may be a single block cast with a recess therein and a base 14 on the lower edge thereof. The recess formed in the outer block is adapted tohave the cable of the elevator system pass ,therethrough. On one side of thereces's, there is a gripping surface 15 which is parallel to the plane of the cable.l On the other side of the recess, there is an inclined surface 16, inclined to the plane of the cable.

The inner member or block is of wedge shape having a gripping surface 17 parallel to the plane of the cable and an inclined surface 18 opposite to the gripping surface which inclined surface is complementary to v the inclined surface ofthe outer block. Thisimier block fits in the recess of theouter block and is adapted to slide along the inclined surface ,7 of theouter block, the gripping surface thereof moving towards or from the gripping surface of the outer block through parallel planes.

At the upper end of the inner block, there is formed a transverse groove which is adapted to .cooperate with a latch which is in the form of a bell crank lever. The bell crank lever, which is ipivoted between its ends, has one arm 19 extending into operative relation with the inner block which arm is bent at the end to form a flange 20 path of acam 23 secured to the elevator car. Asthe cam, when the elevator car reaches the uptween the cable and the drum tosupply the necwhich is adapted to enter the groove in the inner block. On the end of the other arm 2l of the bell crank lever there is rotatably mounted a cam follower 22 which extends into the elevator shaftway. This cam follower extends 'into the I per limit of its movement, engages the cam follower on the latch it rotates the latch about its "theouter block'is mounted on' the overhead strucsecured tothe' outer block 12 by a parallel linkageso thatthe inner block moves into and -out of gripping position throughparallelplanes with pivot so as to withdraw the flange 20 from the groove in the inner block. Upon being released from the latch, the inner block, "under 'the force of gravity acting thereon, slides along the inclined plane and engages the cable. Downward movement of the cable draws the block down- To facilitate movement of the inner block, antifrictionrollers 24-. are-inserted between the complementary inclined surfaces of the inner and outer blocks. When the elevator car starts in the downward. direction, the frictional contact between the gripping surfaces of the inner block and tliec'able carries the inner block upwardly with the cables until the latch has been tripped and the 'ilange thereon extends into the 'gr'o'ove of the inner block in which position of the inner block, the cables are free to move throughthe gripping device.

'When the inner block comesint'o play and the jcables are gripped betweenthe blocks, the momentum of the movingc'ables is transmitted to the blocks' and the energy of the moving cables must be absorbed. If the o'uter'block is'rigid'ly secured to the overhead structure, the shock incide'nt to the stopping and holding of the moving cables would be very severe, and'to avoid this shock and strain upon the overhead" structure,

ture through a resilient support'whi ch includes a stationary block 24 which may besecured to a part 25 of the overhead structure. "Extending from all sides of this stationary block, there are guide plates 26'which'embrace the base 14 of the outer block. A plurality of compression springs Z'T'are placed between the stationary blockof "the support and the base ofthefouter block "12. These springs act'in oppositionto the weight of the cable and are of a strength"proportionalto theweight of the cables. Thus, when "the "inner bloek 13 'moves into the gripping position and the cables are securely gripped between the two the "cables is gradually lessened and the energy dissipated by the compression spring 27.

In Fig. '3 I have shown a modified form "of gripping device' in which theinner' block 13' is age. In this-instance, the outer blbck hasa roove formed therein the'sidesof 'which' 'are paralleltoeach other and to the-fplane o-f the cable. The inner block is' rectangular, as seen in" elevation, and it is movably connected toathe 0 stationary block through two linlrs28 and :29, one adjacent the top of the outer block and-the other adjacent the bottom- 'The links are mounted parallel to each other 'and'form a parallel linkthe gripping surface thereof constantly parallel to the plane of thecable. The operation'of-this gripping device is identical withthat shown in Figs. 1 and 2.

- 1-4; 'From'the above description of my invention, U

tate without transmittingits movementtothe cable as there will not be sufficient friction bei421 conditions, the driving drum cancontinue to-roessary traction; Consequently, it will be impossible for the elevator car to overrun at the upper limit of its movement and be crushed against the overhead structure.

It is obvious that various changes may be made by those skilled in the art in the details of the gripping device above described within the principle and scope of my invention as expressed in the appended claims.

I claim:

1. In an elevator system having an elevator car mounted for travel in a vertical plane, a drum, a counterweight and a cable secured to the car and the counterweight and operatively related to the drum, a cable gripping device for relieving the drum of the weight of the cable in the upper limit of movement of the car comprising a block having a gripping surface adjacent one side of the cable, and a second block cooperating with the first mentioned block and movable with respect thereto into gripping position under the force of gravity acting thereon.

2. In an elevator system having an elevator car mounted for travel in a vertical plane, a drum, a counterweight and a cable secured to the car and the counterweight and operatively related to the drum, a cable gripping device for relieving the drum of the weight of the cable in the upper limit of movement of the car comprising a block having a gripping surface adjacent one side of the cable, a second block having a gripping surface on the other side of the cable movable with respect to and cooperating with the first mentioned block and being movable into gripping position under the force of gravity acting thereon, means for restraining the second mentioned block from moving into gripping position, and means adapted to cooperate with the elevator car for releasing said restraining means.

3. In an elevator system having an elevator car mounted for travel in a vertical plane, a drum, a counterweight for the car and a cable secured to the car and the counterweight and operatively related to the drum, a cable gripping device for relieving the drum of the Weight of the cable in the upper limit of movement of the car comprising a block having a gripping surface adjacent one side of the cable, a second block having a gripping surface on the other side of the cable movable with respect to and cooperating with the first mentioned block and being movable into gripping position under the action of the force of gravity acting thereon, a latch normally restraining the second mentioned block from moving into the gripping position, and means operatively related to the latch and adapted to cooperate with the car to release the movable block.

4. In an elevator system having an elevator car mounted for travel in a vertical plane, a drum, a counterweight for the car and a cable secured to the car and the counterweight and operatively related to the drum, a cable gripping device for relieving the drum of the weight of the cable in the upper limit of movement of the car comprising a member adapted to embrace the cable having a gripping surface adjacent one side of and parallel to the plane of the cable and a surface inclined to the plane of the cable on the opposite side of the cable, a second member adapted to move in the space between the inclined surface of the first mentioned member and the gripping surface thereof, said second mentioned member having an inclined surface complementary to and adapted to cooperate with the inclined surface of the first mentioned member and a gripping surface adapted to cooperate with the gripping surface thereof and being movable into gripping position under the force of gravity acting thereon, a latch adapted to hold the second mentioned member against the force of gravity acting thereon, and means adapted to cooperate with the elevator car for tripping the latch.

5. In an elevator system having an elevator car mounted for travel in a vertical plane, a drum, a counterweight and a cable secured to the car and the counterweight and operatively related to the drum, a cable gripping device for gripping the cable and relieving the drum of the weight of the cable in the upper limit of movement of the car, the gripping device including means for absorbing the shock incident to the stopping of the moving cable.

6. In an elevator system having an elevator car mounted for travel in a vertical plane, a

drum, a counterweight and a cable secured to the car and the counterweight and operatively related to the drum a cable gripping device for gripping the cable and relieving the drum of the weight of the cable in the upper limit of movement of the car, and a resilient support for the gripping device for absorbing the shock incident to the stopping of the moving cable.

7. In an elevator system having an elevator car mounted for travel in a vertical plane, a drum, a counterweight and a cable secured to the car and the counterweight and operatively related to the drum, a cable gripping device for gripping the cable and relieving the drum of the weight of the cable in the upper limit of movement of the car, and a support for the gripping device including means for absorbing the shock incident to the stopping of the moving cable.

8. In an elevator system having an elevator car mounted for travel in a vertical plane, a drum, a counterweight and a cable secured to the car and the counterweight and operatively related to the drum, a cable gripping device for gripping the cable and relieving the drum of the weight of the cable in the upper limit of movement of the car, a support for the gripping device including a plurality of compression springs acting upon the gripping device and adapted to absorb the shock incident to the stopping of the moving cable.

9. In an elevator system having an elevator car mounted for vertical travel, a drum, a counterweight and a cable secured to the car and the counterweight and operatively related to the drum, a cable gripping device for relieving the drum of the weight of the cable in the upper limit of movement of the car comprising a block having a gripping surface adjacent one side of the cable, a second block having a gripping surface on the other side of the cable movable with respect to and cooperating with said first mentioned block and adapted to be moved into gripping position by the force of gravity acting thereon, a support for the gripping device including a plurality of compression springs acting upon the gripping device and adapted to absorb the shock incident to the stopping of the moving cable.

ALVA B. SEE. 

